Broadway Kyle J, Pyron Mark, Gammon James R, Murry Brent A
Institute for Great Lakes Research, Biology Dept., Central Michigan University, Mount Pleasant, MI 48858, United States of America.
Department of Biology, Ball State University, Muncie, IN 47306, United States of America.
PLoS One. 2015 Apr 22;10(4):e0124954. doi: 10.1371/journal.pone.0124954. eCollection 2015.
As the intensity and speed of environmental change increase at both local and global scales it is imperative that we gain a better understanding of the ecological implications of community shifts. While there has been substantial progress toward understanding the drivers and subsequent responses of community change (e.g. lake trophic state), the ecological impacts of food web changes are far less understood. We analyzed Wabash River fish assemblage data collected from 1974-2008, to evaluate temporal variation in body-size structure and functional group composition. Two parameters derived from annual community size-spectra were our major response variables: (1) the regression slope is an index of ecological efficiency and predator-prey biomass ratios, and (2) spectral elevation (regression midpoint height) is a proxy for food web capacity. We detected a large assemblage shift, over at least a seven year period, defined by dramatic changes in abundance (measured as catch-per-unit-effort) of the dominant functional feeding groups among two time periods; from an assemblage dominated by planktivore-omnivores to benthic invertivores. There was a concurrent increase in ecological efficiency (slopes increased over time) following the shift associated with an increase in large-bodied low trophic level fish. Food web capacity remained relatively stable with no clear temporal trends. Thus, increased ecological efficiency occurred simultaneous to a compensatory response that shifted biomass among functional feeding groups.
随着环境变化在地方和全球尺度上的强度和速度不断增加，我们必须更好地理解群落转变的生态影响。虽然在理解群落变化的驱动因素和后续响应（如湖泊营养状态）方面已经取得了重大进展，但对食物网变化的生态影响却知之甚少。我们分析了1974年至2008年收集的瓦巴什河鱼类群落数据，以评估体型结构和功能组组成的时间变化。从年度群落大小谱得出的两个参数是我们的主要响应变量：（1）回归斜率是生态效率和捕食者 - 猎物生物量比的指标，（2）谱高程（回归中点高度）是食物网容量的代理指标。我们检测到至少在七年时间内发生了一次大型群落转变，其定义为两个时间段内主要功能摄食组的丰度（以单位努力捕捞量衡量）发生了巨大变化；从以浮游动物 - 杂食动物为主的群落转变为底栖食虫动物为主的群落。转变后生态效率同时增加（斜率随时间增加），这与大型低营养级鱼类数量增加有关。食物网容量保持相对稳定，没有明显的时间趋势。因此，生态效率的提高与功能摄食组之间生物量转移的补偿性响应同时发生。
